Understanding Catchment‐Scale Forest Root Water Uptake Strategies across the Continental US through Inverse Ecohydrological Modeling

Abstract

Trees influence the partitioning of water between catchment water yield and evapotranspiration through mediation of soil water via Root Water Uptake (RWU). Recent research has estimated the depth of RWU for a variety of tree species at plot scales with measurements of stable isotopes in water and sap‐flux. Though informative, there are some challenges bridging the gap between plot‐ and catchment‐scale water fluxes. We estimated catchment‐scale tree RWU behavior for 139 forested catchments across the continental United States from continuous streamflow records with inverse ecohydrological modeling. Our catchment‐scale RWU estimates agreed well with existing plot‐scale research. Monoculture catchments dense with trees reliant on shallow soil water exhibited reduced transpiration losses compared to deep‐rooted and mixed‐species forests within the Budkyo framework. This research highlights the importance of representing plant characteristics that define RWU control of transpiration in land surface and earth systems models.